Good receiver
At least some MiFi devices have much better phone-side radios than my phone (Galaxy S II). I use the phone as a hotspot a lot and it seems to work OK, need to put it near the window sometimes. In two cases I have witnessed (different MiFi box, different location) MiFi device gets good signal when phone will not get any internet at all.
In one of the cases, Three gave an acquaintance a free MiFi when threatened with contract cancellation due to poor signal at home with dongle. I was highly sceptical but it actually worked. Went from unusable with dongle (on long USB lead to window location) to satisfactory with MiFi.
One of the Mifi devices was Huawei E5332.